The following abbreviations are herewith defined, at least some of which are referred to within the following description of the prior art and the present invention.    3GPP 3rd Generation Partnership Project    AAA Authentication, Authorization, Accounting    AF Application Function    AN Access Network    AP Access Point    BBF Broad-Band Fixed Network    BNG Broadband Network Gateway    BPCF Broadband Policy Control Function    BRAS Broadband Remote Access Server    DSLAM digital subscriber line access multiplexer    EDGE Enhanced Data rates for GSM Evolution    EPC Evolved Packet Core    E-UTRAN Evolved Universal Terrestrial Radio Access Network    GERAN GSM EDGE Radio Access Network    GSM Global System for Mobile Communications    HSS Home Subscriber Server    IMSI International Mobile Subscriber Identity    IP Internet Protocol    IP-CAN IP-Connecting Access Network    NS Non-seamless    OCS Online Charging System    OFCS Offline Charging System    ONT Optical Network Terminal    PCC Policy and Charging    PCRF Policy and Charging Rules Function    PDN GW Public Data Network Gateway    PDP Policy Decision Point    QoS Quality of Service    RG Residential Gateway    SPR Subscriber Profile Repository    UDR User Data Repository    UE User Equipment/User Terminal    UMTS Universal Mobile Telecommunications System    UTRAN UMTS Radio Access Network    WLAN Wireless Local Area Network
Referring to FIG. 1 (PRIOR ART), there is a basic diagram of an exemplary telecommunications architecture 100 used to explain a problem that occurs during what is known as a NS-WLAN offload scenario and in particular the problem relates to the establishment of an IP-CAN session 102 for a UE 104 between a BPCF 106 associated with a fixed broadband access network 108 (BBF domain 108) and a PCRF 110 associated with an evolved packet core network 112 (EPG network 112). In the NS-WLAN offload scenario, the UE 104 has accessed the fixed broadband access network 108 via a WLAN access point 113 on a customer premises network 114 and requests to offload traffic 116 through the WLAN access point 113, the fixed broadband access network 108 to a 3GPP operator network 118 (e.g., Internet) without the traffic 116 being routed through the EPC network 112 (EPC domain 112). During the NS-WLAN offload scenario, the PCRF 110 is to provide policy control via the IP-CAN session 102 for the traffic 116 that the UE 104 offloads in the BBF domain 108 but this traffic 116 is not routed through the EPC network 112. A more detailed discussion about the NS-WLAN offload scenario and the problem associated with establishing the IP-CAN session 102 for the NS-WLAN offload scenario are discussed below.
The technical specification 3GPP TS 23.203 (version V11.4.0)(2011-12) (the contents of which are incorporated by reference herein) discloses a Policy and Charging Architecture, PCC 120, in the EPC network 112, which allows among other features the application of charging and QoS policy rules to data flows of data sessions of their users. The PCC 120 architecture disclosed therein comprises, among other entities, a Policy and Charging Rules Function 110 (PCRF 110), and a Policy and Charging Enforcement Function 122 (PCEF 122). Briefly: the PCRF 110 behaves as a Policy Decision Point (PDP), or policy server, to store policies and determine which policies are to be applied in each case, while the PCEF 122 behaves as Policy Enforcing Point (PEP) of those policies. The EPC network 112 is arranged to provide telecommunication services to user terminals (UEs) irrespectively if they connect from the so called “3GPP access networks” (e.g. GERAN, UTRAN, E-UTRAN) or from the so called “non-3GPP access networks” (e.g. fixed access network, wireless local area network, WLAN, or mixing of wireless and fixed access networks, such as WLAN access points 113 which are connected to the fixed broadband access network 108).
The PCC 120 architecture disclosed by 3GPP TS 23.203 V11.4.0 (2011-12) also envisages a Broadband Policy Control Function 106 (BPCF 106) which is used when the 3GPP EPC domain 112 interworks with the broad-band fixed network domain 108 (BBF domain 108), which can comprise WLAN access points 113. The BPCF 106 is also a policy control entity, but is located in the fixed broadband access network 108, and can cooperate via the so called “S9a” interface 124 with the PCRF 110 which belongs to the 3GPP EPC domain 112 when in interworking scenarios.
The technical specification 3GPP TS 23.402 (V11.1.0; 2011-01) (the contents of which are incorporated by reference herein) includes a description of the scenario where a 3GPP UE 104 accesses via the WLAN access point 113 and traffic 116 is offloaded in the local network (fixed broadband access network 108) without being routed via the Evolved Packet Core (EPC) network 112. This scenario, referred to as “Non-Seamless WLAN offload” (NS-WLAN offload), is further considered in other 3GPP documents as discussed below.
In relationship to interworking scenarios with the 3GPP EPC network 112 comprising the PCC 120 architecture, there is a study document addressing the support of BBF access interworking. This study document is referenced as 3GPP TR 23.839 (V1.4.1) (2011-12) (the contents of which are incorporated by reference herein), and discloses (e.g., in the so called “Building Block II” section) how to provide policy control for traffic of the UE 104 connected to the WLAN access point 113 that resides beyond the fixed broadband access network 108 (BBF domain 108) which is offloaded iii the BBF domain 108 (e.g. towards the internet 118), as well as for the traffic 126 which is instead routed by the BBF domain 108 towards the 3GPP EPC network domain 112. The 3GPP TR 23.839 (V.1.4.1) (2011-12) discloses in e.g. chapter 6.1.1.1, the telecommunication architecture arrangements, and signaling interfaces (e.g. the “S9a” interface 124), which are later referred to and described herein.
The telecommunication architectural reference models described in 3GPP TR 23.839 (V.1.4.1) (2011-12)'s chapter 6.1.1.1 shows various architecture scenarios for accessing the EPC network domain 112 through WLAN access points 113 connected to the BBF domain 108 which can allow performing a NS-WLAN offload with respect to the traffic 116 of the UE 104 (only one shown) connected to the BBF domain 1108. In all these scenarios, the S9a interface 124 (S9a reference point 124) between the BPCF 106 and the PCRF 110 is used to provision policies for NS-WLAN offloaded traffic 116 and/or to request admission control for EPC routed traffic 126.
The 3GPP TR 23.839 (V.1.4.1) (2011-12) defines that the policies (i.e. information making up policy rules for controlling charging and/or QoS aspects for data flows 116 and 126 originating and/or terminating in UEs 104) to be enforced for offloaded traffic 116 can be provided by the PCRF 110 of the 3GPP EPC network 112 to the BPCF 106 of the BBF domain 108. The IP-CAN session 102 that is used to provision these policies can already be established when the UE 104 attaches to the fixed broadband access network 108 (BBF domain 108) and authenticates before the network entities of the EPC network 112. The IP-CAN session 102 for offloaded traffic 116 then remains established regardless of whether the UE 102 offloads any traffic 116 or not.
Furthermore, the information flows in 3GPP TR 23.839 (V1.4.1)(2011-12) (the contents of which are incorporated by reference herein) shows that the IP-CAN session 102 for the traffic 116 that can be eventually offloaded for the UE 104 by the BBF domain 108 is always established—through the “S9a” interface 124 between the BBF domain 108 and the 3GPP EPC network 112—at the Initial Attach of the UE 104 to the BBF domain 108 (e.g. via a WLAN access) and remains established until the UE 104 detaches, moves to another access, or a server entity in any of the network domains 108 and 112 decides to detach the UE 104. The details of an “Initial Attach” of the UE 104 in this particular interworking situation are shown in clause 6.3.1 of 3GPP TR 23.839 (V1.4.1)(2011-12), and details of a subsequent “Detach” of the UE 104 are shown in clause 6.3.3 of 3GPP TR 23.839 (V1.4.1)(2011-12).
The results of the study document 3GPP TR 23.839 are currently being incorporated in the 3GPP technical specification TS 23.139 (V1.2.0; 2011-11), which specifies features to be implemented by servers of the BBF domain 108 and of the 3GPP EPC network 112 in an interworking scenario as the one studied by the aforementioned 3GPP TR 23.839 (V.1.4.1)(2011-12).
Hence, according to the current solutions (e.g., 3GPP TS 23.139) the IP-CAN session 102 for controlling UE traffic 116 that can be offloaded directly from the BBR domain 108 is established (for the UE 104 connected to the BBF domain 108 e.g. via a WLAN access point 113) between servers of the BBF domain 108 and servers of the 3GPP EPC network domain 112, and the IP-CAN session 102 remains established between the involved nodal entities namely the BPCF 106 and PCRF 110 in these different network domains (i.e. the BBF domain 108 and the 3GPP EPC network domain 112) regardless of whether the UE 104 offloads any traffic 116 or not. This particular fact causes more signaling between these entities namely the BPCF 106 and PCRF 110 thereby adversely affecting their performance.
More specifically, the current PCC information flows (e.g. as generally defined by 3GPP TS 23.203 (V11.4.0)(2011-12) for the 3GPP EPC network 112, and the more specific ones envisaging interworking scenarios between the 3GPP EPC network 112 and the BBF domain 108) all envisage solutions wherein the IP-CAN session 102 is established for requesting and obtaining policy rules as soon as the UE 102 is assigned an IP address. This is illustrated, for example, in the Initial Attach information flows disclosed by the 3GPP TR 23.839 (V.1.4.1)(2011-12) where the successful authentication of the 3GPP UE 104 and the UE's IP address assignment by the BBF domain 108 triggers the establishment of the IP-CAN session 102 for an eventual UE's NS-WLAN offloaded traffic 116.
However, for the case of the UE 104 offloading the traffic 116 at the fixed broadband access network 108 (BBF domain 108), the UE 104 may not be authorized to offload this traffic 116, so that the establishment of the IP-CAN session 102 to request policy rules as soon as the UE 104 is assigned an IP address by the fixed broadband access network 108 (BBF domain 108) can result in a useless provision of policy rules for unauthorized traffic. It may also be the case that the UE 104 is permitted to offload traffic 116 in the fixed broadband access network 108 (BBF domain 108)—e.g. in certain cases—but the EPC operator does not want to provide policy control via the S9a interface 124 (i.e. communicating policy rules to the BPCF 106 in the BBF domain 108) for such traffic 116 depending on the circumstance (e.g. depending on IP-CAN type utilized by the UE 104, or depending on the assigned local IP-address assigned to the UE 104). Or, the EPC operator may only want to provide policy control via the S9a interface for the UE's EPC routed traffic 126 but not for the traffic 116 offloaded through the fixed broadband access network 108.
As a result, the existing solution that the IP-CAN session 102 for offloaded traffic 116 is always established may result in a situation that many IP-CAN sessions 102 are established for UEs but never used. This is a waste of resources in both the BPCF 106 and the PCRF 110. Accordingly, there is a need to address this shortcoming and other shortcomings associated with establishing the IP-CAN session 102 for the NS-WLAN offload scenario. This need and other needs are satisfied by the present invention.